The present invention relates to an intake system for an internal combustion engine of a motor vehicle having an intake for untreated air, an untreated air pipe connected to the untreated air intake and communicating with the internal combustion engine, and a water separator adjoining the untreated air pipe, in which a swirl can be produced inside the untreated air pipe.
JP 59203860 discloses an intake system for an internal combustion engine of a motor vehicle, which is provided with an air intake. The air intake is arranged in the front area of the vehicle, so that air is forced into the air intake during travel. From the air intake, the air is guided tangentially in a connecting pipe to a cylindrical water separator. Inside the water separator, the air is set into rotation, which causes the water droplets contained in the air to impact against the cylindrical water separator and to be discharged via the automatic water discharge valve arranged at the lower end of the water separator. The dehumidified air flows through a connecting line centrally disposed in the water separator into an intake line, which is connected to the internal combustion engine. The connecting line protrudes into the water separator, so that the air, prior to entering the connecting line, must change its radial flow direction to an axial flow direction.
This abrupt change in the flow direction causes a substantial pressure loss in the intake system, so that less air can be supplied to the engine, or the intake system has to be more amply dimensioned. Further, there is a risk that water droplets may be deposited along the connecting line, which protrudes into the water separator. These water droplets are then entrained by the air entering the connecting line, so that the separation efficiency of the water separator is impaired.
The object of the invention is to provide an air intake which overcomes the aforementioned drawbacks.
A particular object of the invention is to provide an air intake which can effect separation of water droplets from the aspirated air without an excessive pressure loss.
Another object of the invention is to provide an air intake which can maintain a high degree of separation efficiency and avoid re-entrainment of separated water droplets.
A further object of the invention is to provide an air intake which can effectively separate water droplets from aspirated air while taking up only a small amount of space.
These and other objects are achieved by the invention as described and claimed hereinafter.
In particular, the objects have been achieved in accordance with the present invention by providing an intake system for an internal combustion engine of a motor vehicle comprising an untreated air intake, an untreated air pipe connected to the untreated air intake, and a water separator adjoining the untreated air pipe, wherein a swirl can be produced inside the untreated air pipe, and wherein the untreated air pipe communicates with the internal combustion engine, and wherein the water separator comprises an inner pipe and an outer pipe, which are arranged in axial direction to one another, and the inner pipe projects into the outer pipe, and the outer pipe is provided with a water outlet.
The intake system for an internal combustion engine of a motor vehicle according to the invention comprises at least one intake for untreated air and an untreated air pipe, which is connected to the untreated air intake and communicates with the internal combustion engine. In special embodiments, the untreated air intake is arranged in the front area of the motor vehicle, so that the intake air is forced into the intake system during travel and more air can be supplied to the internal combustion engine. Since water spray produced in this frontal air intake (particularly small water droplets mixed with the intake air, caused for instance by another vehicle driving ahead, or a wet road, or a strong rainfall) will reach the intake system, a water separator connected to the untreated air pipe is provided. The untreated air pipe is configured in such a way that a swirl can be produced in it. This swirl can be generated, for instance, by a special configuration of the untreated air pipe, particularly by two 90xc2x0 bends in the 3-dimensional volume. It is also possible, however, to provide means for producing such a swirl, e.g., guide vanes that are arranged inside the untreated air pipe. The swirl must set the intake air into a rotation that is sufficient to fling the water droplets contained in the intake air against the wall of the untreated air pipe. This causes the water droplets to be deposited along the wall, so that the intake air in the central area of the untreated air pipe no longer contains any water droplets.
The water separator comprises an inner pipe and an outer pipe, which are arranged in axial direction, particularly coaxially, to one another. The imaginary center axes can be mutually offset in their height as well as in their angle to one another. An advantageous embodiment provides for a concentric configuration of the imaginary center axes. The inner pipe together with the outer pipe can be constructed as an integral part or a multi-sectioned part. The water separator can, for instance, be made entirely of plastic or metal, or it can be formed from a combination of different materials. Due to the construction of the water separator, which is mutually arranged in axial direction, the intake air within the water separator is not deflected, so that no pressure losses occur. Further, the water separator is arranged coaxially to the untreated air intake. The inner pipe protrudes into the outer pipe, and the outer pipe is provided with a water outlet through which the separated water is removed from the intake system. To discharge the water from the outer pipe, the water outlet can be connected, for instance via a connecting line, to a water collecting basin, a water consumer, or to the environment. The cross-sections of the untreated air pipe as well as of the inner pipe and the outer pipe can have any desired configuration; for example, oval or polygonal cross sections may be used. Advantageously, cross sections, which only negligibly affect the swirl, are selected. Particularly advantageous is a circular embodiment of the cross sections, which does not influence the swirl and thus produces the lowest friction losses and the best separation results.
The water droplets that have already been deposited along the wall of the untreated air intake are transported by the airflow to the water outlet, where they are discharged from the intake system. The intake system according to the invention permits simple and cost-effective water removal from the aspirated air. It makes it possible to minimize pressure losses and requires hardly any installation space for the water-separating components. Moreover, this type of water separation is maintenance-free.
Advantageously, the outer pipe has a diverging or expanding separation area, so that the water deposited along the wall can no longer be entrained into the intake air. The expanding separation area is configured in such a way that the airflow does not stall. For instance, diverging angles of 0xc2x0 to 60xc2x0 may be realized. Angles of divergence ranging from 20xc2x0 to 30xc2x0 create particularly advantageous separation efficiencies.
According to another embodiment of the invention, the inner pipe has a diverging or expanding deceleration area to compensate pressure losses in the intake air. In the deceleration area, the cross-section is enlarged, so that the intake airflow is slowed and a pressure increase is produced. This improves the charging of the intake system and thus the internal combustion engine.
In a further variant of the invention, a splash collar is arranged on the inner pipe in order to prevent the separated water from flowing back into the dehumidified intake air. This splash collar is configured in such a way that it prevents water from reaching the inner pipe, even if the amount of collected water is relatively large.
Advantageously, the water outlet is tangentially arranged in swirl direction, which causes the separated water to be pressed into the water outlet by the swirl. A funnel-shaped water outlet is particularly advantageous, since the water reaches the water outlet not only due to the swirling force but also due to its own weight.
In accordance with a further embodiment of the invention, the water outlet is provided with a discharge valve which opens the water outlet in only one direction and is provided with a pressure control element, so that no air can be sucked in via the water outlet. The required opening pressure of the discharge valve corresponds to at least the resistance in the untreated air pipe.
In one specific embodiment of the invention, the inner pipe is connected directly to a filter housing disposed downstream from the water separator, so that the dehumidified air can flow directly into the filter housing where it is filtered. The connection of the water separator to the filter housing makes it possible to reduce the number of components, since it eliminates the connecting pieces for the water separator.
According to an advantageous embodiment of the invention, the outer pipe has a cylindrical outer area with a first diameter. This cylindrical outer area is connected on the one end to the untreated air pipe and on the other end to the separation area. The separation area is conical and has a second diameter, which is greater than the first diameter. Further, the outer pipe has a discharge area with a third diameter, which is connected to the second diameter. The third diameter, however, is larger than the second diameter so as to produce a water trailing edge. This water trailing edge prevents the separated water from getting into the inner pipe. The inner pipe has a cylindrical inlet area with a first inside diameter, which inlet area protrudes beyond the water trailing edge. The inlet area is connected to a conical deceleration area. The deceleration area is adjoined by an outlet area with a second inside diameter on the opposite side from the inlet area. The first inside diameter is smaller than the second inside diameter. Furthermore, the inner pipe is connected to the outer pipe so as to form a seal.
Advantageously, the first diameter of the outer pipe is larger than the first inside diameter of the inner pipe. This has the effect that only the dehumidified air reaches the intake area, and water droplets are not entrained.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either individually or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.